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Performance Verification
1780R-Series Service Manual
4–33
c. Set the 1780R-Series WFM HORIZONTAL buttons to TWO–LINE.
d. Press the CONFIGURE button to On. Check that COUPLING–DC and
DC RESTORER–OFF are selected on the Configure menu.
e. Set the sine wave oscillator amplitude control so that the display on the
Waveform CRT is 100 IRE for NTSC (700 mV for PAL).
f. Select WFM HORIZONTAL–TWO–FIELD mode.
g. Select DC RESTORER–SLOW on the CONFIGURE menu.
h. Check that the hum signal is greater than 90 IRE for NTSC (643 mV for
NTSC or PAL) as displayed on the Waveform CRT.
i. Select DC RESTORER–FAST.
j. Check that the hum signal is less than 5 IRE in amplitude for NTSC
(36 mV for NTSC or PAL).
k. Move the hum signal to each of these 1780R-Series INPUT connectors:
CH B1, CH B2, and CH B3. Use the appropriate INPUT button to select
each of these inputs.
l. Check Use parts g. through j. of this step as a guide to check hum
attenuation for the CH B1, CH B2, and CH B3 INPUTs.
m. Move the sine wave hum signal from the 1780R-Series CH B3 INPUT
connector to the left front-panel PROBE input connector.
n. Use the appropriate 1780R-Series INPUT button to select PROBE.
Select PROBE–X1 on PAGE 2 of the Configure menu.
o. Check Use parts e. and g. through j. of this step to check hum attenua-
tion for the PROBE input.
p. Set the 1780R-Series control and menu as follows: INPUT–CH A and
DC RESTORER–OFF.
q. Disconnect the hum signal from the PROBE connector.
23. Check Vertical Overscan
Requirement: With 1 V p-to-p NTSC or PAL Modulated Sin
2
composite
video signal applied to the 1780R-Series CH A INPUT, there should be less
than 7 mV variation in the chroma baseline when the signal baseline is
positioned anywhere within the 1 V vertical scan area.
a. Connect the television test signal generator Modulated 2T Pulse & Bar
signal (12.5T NTSC, 10T PAL), through a 75 W feed-through termina-
tor, to the 1780R-Series CH A INPUT. Check that the Black Burst signal
is applied to the EXT REF connector.